At least two reflector antenna assemblies are known for generation of contoured beams in dual linear polarization. A first such known assembly is an assembly of dual offset shaped reflectors in which the polarization reuse is obtained from a high quality feed interfaced to an ortho mode transducer (OMT) feeding a dual reflector assembly of inherently low cross polarization. In such an assembly an offset subreflector, preferably ellipsoidal cancels the cross polarization of an offset solid profiled main reflector which generates the required beam shape. The subreflector and main reflector generally face towards one another and are spaced apart with corrugated feed interfaced to the orthomode transducer being located between the two reflectors and pointing towards the subreflector. Thus radiation from the feed is reflected from the subreflector to the solid profiled main reflector. Such a known dual offset shaped reflector assembly is relatively cumbersome in size, is greatly influenced by thermal misalignment due to the use of a subreflector, requires a very complex feed means and is unable to generate different contoured beam shapes on the two polarizations.
Contoured beams may also be generated in dual linear polarization by the use of a conventional gridded antenna assembly. Such an assembly utilizes two gridded reflectors in which the front is transparent to radiation intended for reflection from the rearmost antenna. Both reflectors are of simple conic section profile which requires the use of complex multiple feed clusters to generate contoured beams. The use of such complex multiple feed clusters has the disadvantage of producing feed mutual coupling with difficult to predict effect resulting in discrepancies in pattern shape between predicted and measured beam contours or patterns. Such multi feed antenna assemblies also suffer from beam forming network losses with consequent reduction in gain and the difficulty in generating overlapping beams without feed sharing.